Generally, in the former print apparatus, a print head that is a record means is loaded onto a part called a carriage, and an image is recorded through performing round moving and impacting of the print head in a width direction of print paper that is orthogonal with a transport direction of the print paper. At that time, the print head protrudes a plurality of dot pin wires, and performs a print through transferring ink of an ink ribbon from a ribbon mask hole of a ribbon protector to the paper inhaled between a platen and the ribbon protector.
Then, in this kind of print apparatus, a mechanism (for example, referring to patent document 1) is furnished in which the ink ribbon is always sent in a direction, the carriage and a ribbon drive axle is driven by a motor, and the ink ribbon is sent in a feed amount that is less than a feed amount of a carriage so as to keep relativity movement speed of the ink ribbon with respect to the print head constant for using the whole in ribbon uniformly. For example, the mechanism is furnished that transports drive power from the carriage to the ribbon drive axle so that the feed amount of the ink ribbon becomes ⅓ when the feed amount of the carriage is served as 1.
Patent document 1: Japan patent publication of No. 08-192560
However, in the former print apparatus, when the print is performed by moving the carriage only “A” in a positive direction (same direction) with respect to the ink ribbon movement direction, because only “A/3” of the ink ribbon is sent, the ribbon use region becomes “A−(A/3)” and the print is performed by repeatedly impacting on the narrow ribbon use region with respect to a print movement amount “A”, a print result becomes to be light (FIG. 6).
On the other condition, when the print is performed by moving the carriage only “A” in a reverse direction with respect to the ink ribbon movement direction, because only “A/3” of the ink ribbon is sent, the ribbon use region becomes “A+(A/3)”, and the print is performed by not repeatedly impacting on the wide ribbon use region with respect to a print movement amount “A”, a print result becomes to be dark (FIG. 7).
Therefore, when such print of the positive direction and the reverse direction is repeated, because one part of the ink ribbon is used repeatedly there is a problem that print density unevenness occurs.
This kind of the print density unevenness is not a serious problem when a character data whose density is low is printed. However, when an image data whose density is high is printed, the print density unevenness will remarkably appear.